Experiment 2 was largely a control experiment with each trial composed of two sequentially presented flow patterns of the same type. There are two flashes below to demonstrate the basic stimuli used in this experiment. The upper flash is a schematic representations of two expanding optic flows in the first and the second intervals. The lower flash is a schematic representations of two contracting optic flows in the first and the second intervals. Participants' task is to indicate which interval contains a flow with its FOC/FOE closer to the central fixation point (equal close in these examples). In both flashes, the two flow patterns are presented only in one of the four visual quadrants. In the other three conditions, the two flow patterns were presented in the other three visual quadrants. The aim of this manipulation was to investigate whether the perceived flow centre shift found in Experiment 1 was genuinely due to the differences between a contracting and an expanding flow patterns.